Cryogenic fuel combustion engines

ABSTRACT

The invention relates to systems enabling the use of cryogenic fuels within combustion engines, including jet engines.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of priority of and is a continuation application under 35 U.S.C. § 120 based upon co-pending U.S. patent application Ser. No. 14/409,490 filed on Dec. 19, 2014, which is a national phase application under 35 U.S.C. § 371 based upon International Application No. PCT/CA2013/000581 filed on Jun. 14, 2013, which claims the benefit of priority to U.S. provisional application 61/661,940 filed on Jun. 20, 2012. The entire disclosures of the prior applications are incorporated herein by reference.

FIELD OF THE INVENTION

The invention relates to systems enabling the use of cryogenic fuels within combustion engines, including jet engines.

BACKGROUND OF THE INVENTION

As is well known, natural gas is a plentiful and relatively inexpensive energy product. It is widely used in a large number of industries including power generation, home heating, transportation, fertilizers, hydrogen generation as well as in the manufacture of many products.

To date, the use natural gas in the transportation industry has been generally limited to compressed natural gas (CNG) that has been utilized within internal combustion engines (ICEs). In these applications, a compressed gas tank stores the natural gas and the natural gas is delivered to the chambers of the ICE primarily through the release of pressure from the gas tank. Generally, a CNG vehicle is advantaged over gasoline type vehicles by improved emissions quality; however a CNG is disadvantaged by the overall energy density of the CNG within a compression tank. In addition, there is also a general perception amongst the public that CNG as a fuel within a compression tank is substantially more dangerous than a liquid fuel in an un-pressurized tank due to the perceived potential for explosion with a compressed gas.

Liquid natural gas (LNG) as an energy source provides a number of advantages over CNG particularly in terms of energy density. More specifically, LNG has approximately 2.4 times the energy density of CNG. Advantageously, LNG also has an energy density on a mass basis approximately 50% higher than of gasoline. However, on a volumetric basis, the energy density of LNG is about 50% that of gasoline. As such, for a given mass of LNG, the LNG stores approximately 50% more energy in comparison to an equivalent weight of gasoline.

Thus, as a form of vehicular energy, notwithstanding the volumetric disadvantage of LNG compared to gasoline, LNG is attractive as a vehicular fuel as it contains approximately 50% more energy than gasoline on a weight basis.

Moreover, as a relatively pure product that does not require the level of refining of liquid petroleum products, natural gas and LNG are also very attractive from a cost perspective.

As is known, the economics of LNG as an energy sources are complex in that many factors go into the determination of an LNG price including the base price of the natural gas, the costs of the liquefaction process, transportation and storage costs as well as jurisdictionally imposed taxes. End product capital costs of the equipment using the LNG are also a factor in the final cost of delivering the LNG energy sources to the consumer. However, with the assumption that transportation costs are a small component of the price of LNG, and that many of above costs are comparable to gasoline, the cost of LNG to an equivalent volume of gasoline is approximately 50% of that of gasoline.

In addition to the cost and bulk energy considerations of LNG compared to gasoline, there are also performance considerations associated with the use of LNG within a combustion engine.

In particular, the cryogenic state of LNG has the potential to affect the performance of combustion engines by providing effective cooling within an engine. That is, as is well known, the performance of a combustion engine can be improved by increasing the density of the incoming combustion air. By way of example, intercoolers are used to effect a cooling of combustion air entering an internal combustion engine so as to improve the combustion processes within the engine.

Furthermore, by virtue of the energy required to effect liquefaction of natural gas to LNG, LNG effectively stores energy of vaporization which on conversion from liquid to gas may be used to perform useful work.

SUMMARY OF THE INVENTION

In accordance with the invention, there is provided a jet turbine having a plurality of compressor stages for compressing combustion gas and combusting a fuel, the jet turbine comprising: a cryogenic fuel injector/nozzle for injecting a cryogenic fuel into a cryogenic turbine section, the cryogenic turbine section enabling the vaporization of a cryogenic fuel; and a combustor downstream of the cryogenic fuel injector/nozzle and cryogenic turbine section for combusting vaporized cryogenic fuel wherein combusted cryogenic fuel expands through a combustor turbine operatively connected to upstream compressor stages.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is described with reference to the accompanying figures in which:

FIG. 1 is a schematic diagram of a turbine engine utilizing liquid natural gas as a fuel in accordance with one embodiment of the invention; and,

FIG. 2 is a schematic diagram of a turbine engine utilizing liquid natural gas as a fuel showing the position of fuel injector/nozzles in accordance with one embodiment of the invention.

DETAILED DESCRIPTION OF THE INVENTION

With reference to the Figures, combustion engines utilizing cryogenic fuels are described. More specifically, the technology relates to systems and methods for using cryogenic fuels in combustion engines, including turbine engines. Generally, the engines operate as hybrids of their normal designs that utilize the energy of vaporization of cryogenic fuels as a work force within the engine as well as the combustion of vaporized gas. Importantly, the engines provide various efficiency advantages over other designs of engines by enabling the use of cryogenic fuels within a combustion engine. The engines enable the use of readily available fuels such as LNG which has a higher energy density and lower cost as compared to a liquid hydrocarbon such as gasoline, kerosene or diesel.

Jet Turbine

FIGS. 1-2 describe turbine engine embodiments in which a cryogenic combustible liquid gas (CCLG) is utilized. The turbine engine comprises a turbofan jet engine 1, a fan 2, an engine body 3, a fan nozzle 4, a low pressure compressor 5, a high pressure compressor 6, a cryogenic fluid injector/nozzle 7, a cryogenic turbine section 8, a combustor 9, a combustor turbine 10, an engine nacelle 12 and a core nozzle 11. FIGS. 1 and 2 show slightly different positions of the nozzles 7.

Generally, the cryogenic gas is injected into the engine prior to the combustor sequence. The liquefied gas expands in the cryogenic turbine section 8 as it mixes with incoming air received through fan 2 and low pressure compressor 5. The pressure of expansion is used to rotate turbine blades prior to combustion.

In addition, the cryogenic gas provides a cooling effect to the incoming combustion air that will increase the density of the combustion air prior to reaching the combustors 9 thus enhancing the combustion process.

Downstream of the injector/nozzles, the now vaporized gas is ignited in the combustor 9 wherein the energy of combustion is used to drive combustor turbine blades 10 as in a regular jet engine. The combination of vaporization of liquefied gas and combustion of vaporized gas produces thrust.

Importantly, by virtue of the cooling effects, the temperatures within the compressor stages may be lower, thereby enabling the construction of compressor stages with lower cost alloys.

Although the present invention has been described and illustrated with respect to preferred embodiments and preferred uses thereof, it is not to be so limited since modifications and changes can be made therein which are within the full, intended scope of the invention as understood by those skilled in the art. 

1. A jet turbine having a plurality of compressor stages for compressing combustion gas and combusting a fuel, the jet turbine comprising: a cryogenic fuel injector/nozzle for injecting a cryogenic fuel into a cryogenic turbine section, the cryogenic turbine section enabling the vaporization of a cryogenic fuel; and a combustor downstream of the cryogenic fuel injector/nozzle and cryogenic turbine section for combusting vaporized cryogenic fuel wherein combusted cryogenic fuel expands through a combustor turbine operatively connected to upstream compressor stages.
 2. The jet turbine of claim 1 wherein the cryogenic fuel is liquid natural gas.
 3. The jet turbine of claim 2 further comprising a fan operatively connected to the cryogenic turbine section for receiving incoming air.
 4. The jet turbine of claim 1 further comprising a fan operatively connected to the cryogenic turbine section for receiving incoming air. 